Pin tumbler lock



May 4, 1965 c. A. BAUER PIN TUMBLER LOCK Filed March 14, 1963 Chafles H. Bauev @pwnm, (RM/5M ATTORNEY United States Patent 3,181,320 PIN TUMBLER LQCK Charles A. Bauer, Woodbridge, onn., assignor to Sargent & Company, New Haven, Conn. Filed Mar. 14, 1963, Ser. No. 265,120 8 Claims. (Cl. 70-421) This invention relates to pin tumbler locks and more particularly to a pin tumbler lock having improved resistance and protection against picking.

Pin tumbler locks are usually constructed with a key barrel of generally cylindrical form which fits into a housing or body member. A bolt or locking member is operated by movement of the key barrel relatively to the housing. The key barrel is normally locked to the surrounding housing by means of pins, which are pressed into a locking position by biasing means, such as springs. When these pins, having distinct upper and lower portions known as drivers and tumblers, are set by the proper key such that the points of contact between the drivers and tumblers coincide with the periphery of the key barrel, the key barrel may be rotated.

In pin tumbler locks the usual method of picking is to raise the drivers to the position where the lower edge thereof coincides with the periphery of the key barrel and the housing, thereby leaving the key barrel free to be moved. This method of picking is usually accomplished by applying a force or torque to the key barrel and selectively raising the tumblers with a picking tool, to lift the drivers. The torque is applied to the key barrel so that once a driver is raised to its unlocking position, the key barrel can be moved sufiiciently to provide a ledge upon which the raised drivers may rest to prevent the drivers from falling back into a locking position.

There is a constant effort by lock designers to design a lock which is pick-proof. However, this constant effort on the part of the lock designers seems to lag the increase in skill and determination of lock pickers. Locks may be mechanically designed that they are extremely diificult to pick. However, such designs, for the most part, involve the provision of tumbler mechanisms made to very small tolerances and extremely close fits between coacting parts. The provision of such locks, for the most part, makes the cost of the lock extremely high, and difficult to market because of the extremely high price.

In the past, locks which have a high degree of picking resistance, appear to be designed on the theory that the lock should be difiicult to pick and yet be usable for a long period of time, even after it had been successfully picked or an attempt has been made to pick the lock. This approach, for the most part, neglects the premise that the basic purpose of a lock is to exclude, regardless of whether the lock might be destroyed or rendered inoperable by an attempted picking thereof.

The present invention provides a new and improved pin tumbler lock provided with additional locking means which make it exceedingly difiicult to pick. Locks em bodying the invention are provided with means which permanently lock the key barrel in the lock housing, should an otherwise successful attempt be made to pick the lock. To this end the lock is provided with at least two security pins which, when the key barrel of the lock is turned to a certain extent as by one attempting to pick the lock as aforesaid, serve to interengage both the key barrel and its housing and thereby prevent further rotation of the key barrel to effect unauthorized entry.

An object of this invention is to provide a new and improved pin tumbler lock which is highly resistant to picking.

Another object of this invention is to provide a pin tumbler lock having security means which additionally amaze Patented May 4, P365 lock the barrel against movement if the lock is attempted to be picked.

A further object of this invention is to provide a new and improved pin tumbler lock having security means which permanently lock the key barrel against movement with respect to the housing if the lock is attempted to be picked.

The features of the invention which are believed to be novel are pointed out with particularity and distinctly claimed in the claims appended to and forming part of this specification. However, the invention, both as to its organization and operation, together with further objects and advantages thereof may best be appreciated by reference to the following detailed description taken in conjunction With the drawings in which:

FIG. 1 is a plan view of a lock embodying the invention;

FIG. 2 is a side elevation, in section, of the lock 0 FIG. I seen along section 2-2 of FIG. 1;

FIG. 3 is :a view seen along section 3-3 of FIG. 2;

FIG. 4 is a View seen along section 4-4- of FIG. 2;

FIG. 5 is also a view seen along section 4-4 of FIG. 2 with a key inserted in the key barrel and the key bar-rel rotated in a direction to release the lock;

FIG. 6 is a View seen along section 4-4 of FIG. 2 illustrating the operation of the lock when it is attempted to be picked;

FIG. 7 is a fragmentary sectional view similar to FIG. 6 illustrating a modification of the invention; and

FIG. 8 is also a fragmentary sectional view similar to FIG. 6 illustrating another modification of the invention.

A preferred embodiment of the invention comprises a lock having a housing 10 defining a generally cylindrical bore which receives a key barrel 11 therein. Key barrel 10 has a bolt actuating member or roll back 12 mounted thereon, and defines a key slot 13 at least partially therethrough. In the illustrated embodiment of the invention, the lock is operated by turning the key barrel 11 Within the lock housing 10. However, it will be understood that the invention is applicable to pin tumbler locks wherein the key barrel or an equivalent plug member moves longitudinally with respect to the lock housing. As more clearly illustrated in FIG. 2, the barrel 11 is locked against rotation in the housing by a plurality of biased pin mechanisms each of which comprise a tumbler 14, a coacting driver 15 and biasing means such as a spring 16 urging coacting tumblers and drivers downwardly. Each coacting driver and tumbler and associated spring is positioned in a longitudinally extending well ttla defined in housing 19 and an aligned well 11:: defined in key barrel 11. As more clearly shown in FIG. 3, the Wells 10a are of greater width than key slot 13. The springs 16 react against a retaining plate 17 on housing ltl.

Each of the drivers extend across the periphery 18 of key barrel 11 so that normally the drivers 15 extend into both the key barrel and the housing and prevent rotation of the key barrel in the housing. When a proper key is inserted into slot 13 to permit authorized operation of the lock, the key, by the bites thereon, lifts the tumblers 1 a distance such that the points of contact of the tumblers 14 and their coacting drivers 15 are aligned at the upper edge of the key barrel. The term authorized, as herein used refers to operation of the lock by a proper key as opposed to picking of the lock. When the points of contact between the tumblers 14 and the drivers 15 have been aligned, the key may then be utilized to rotate the key barrel 11 and actuate roll back 12. The structure of the lock, as thus far described, is common to many pin tumbler locks.

In accordance with the invention, means are provided to positively lock the barrel against rotation in the housing if an attempt should be made to pick the lock which is successful in rotating the barrel 11. Such means, in a preferred form, comprise security pins 19 and 20 vertically disposed, as shown, on either side of the longitudinal center line of the barrel 11 and generally transverse thereto. Security pins 19 and 2d are arranged to be received in wells 21 and 22 respectively, defined in the housing and are biased toward the key barrel by means of springs 23 and 24, respectively. The security pin wells are preferably parallel to the tumblerriver wells and each security pin well is adjacent a tumbler-driver well. Retaining plate 17 is formed to overlie wells 21 and 22 and react against springs 23 and 24.

While the security pins 19 and 2% may be individually arranged adjacent any of the tumbler-driver assemblies, the security pins have been shown arranged on either side of coacting tumbler 14a and driver a. Defined in key barrel 11 are security pin receiving wells 25 and 26 arranged to receive security pins 19 and therein upon unauthorized rotation of key barrel 11. The security pin receiving wells and 26 open in substantial alignment with barrel wells 11a and longitudinally extend from the upper surface of key barrel 11 at a small angle from the vertical plane. This angle is selected to be less than the angle of rotation required of key barrel 11 to unlock a lock.

As more clearly seen in FIG. 5, when a key 27 is inserted into key slot 13 to raise the line of contact between tumblers 14 and their coacting drivers 15 to coincide with periphery 18, authorized operation of the lock is permitted and key barrel 11 may be rotated to actuate roll back 12 and unlock the lock. It may be seen when a proper key is inserted for authorized operation, that tumbler 14a is forced by key 27, beneath and against security pin 19, thereby preventing security pin 19 from being inserted into well 25. In a similar manner, if key barrel ll were rotated in the opposite direction, with a proper key therein to permit authorized operation, tumbler 14a would engage security pin 20 and prevent entry thereof into well 26.

Assume now that an attempt is made to pick the lock. If the lock picker is successful in utilizing a picking tool to align the point of contact between the tumblers and the drivers along periphery 18 and commences to rotate key barrel 11, tumbler 14a will not be held up in contact with security pin 19 and will not be positioned to block security pin 19 from entry into well 25. Therefore, when key barrel 1]. has been rotated a predetermined distance security pin 19 will be forced by gravity and spring 23 into well 25. It will be noted that security pin 19 is of sutficicnt length to fit into well 25 and extend beyond key barrel 11 into housing 10. Moreover, it will be noted that tumbler 14a is selected to be of a longitudinal dimension which will not interfere with entry of security pin 19 into well 25. While the operation of security pin 19 into well 25 has been illustrated and specifically described, it is apparent that should the cylinder 11 be rotated in the clockwise position, as shown in FIG. 6, while unauthorized operation is being attempted, security pin 29 will descend into well 26 and prevent key barrel 11 from further rotation.

FIG. 7 illustrates a modified form of the invention utilizing security pins 19a and 20a, which are undercut centrally thereof, so that any attempt to move tumbler 14a in such a manner as to force security pin 1% upwardly would result in tumbler 14a extending into the undercut portion of security pin 19:: and provide a wedging action which would prevent upward movement of security pin 1%.

FIG. 8 illustrates another modification of the security pin wherein a security pin 19b is provided with a small undercut 23 positioned such that a leading edge of tumbler 14:: will be received therein if it is forced upwardly in slot 13 in an attempt to lift security pin 1% out of well 25.

It will be noted that if unauthorized operation of the lock is attempted and one of the security pins is inserted into a well provided therefor in the key barrel, the lock must be destroyed to gain entry through the door or other device which the lock is intended to protect. While the lock must thus be destroyed and presents a loss, it has successfully served its purpose in preventing unauthorized entry through the door or other opening which it protects.

It will be understood that the security pins may be arranged adjacent any one of the coacting drivers and tumblers, and the lock may be designed so as to require only one security pin. The security pins 19 and 20 could be arranged adjacent different driver and tumbler assemblies. Moreover, a security pin or pins could be utilized with a lock having only one driver-tumbler assembly. Various other modifications may be made to the disclosed embodiments of the invention without departing from the spirit and scope of the invention.

Accordingly, it is intended that the appended claims cover all modifications of the disclosed embodiments of the invention as well as other embodiments thereof which do not depart from the spirit and scope of the invention.

1. A lock comprising a housing, a key barrel mounted in said housing for rotation therein, a pin tumbler mechanism locking said barrel against rotation therein comprising at least one coacting tumbler and driver received in a well defined by said housing and said barrel and means biasing said tumbler and driver in a locking position, a security Well defined in said barrel and extending at a small angle from said driver-tumbler assembly such that said well approaches a vertical position upon asmall degree of rotation of said barrel, and a security pin carried in a well defined in said housing, said security pin extending transversely of the longitudinal axis of said barrel and being arranged with respect to said security well such that upon unauthorized rotation of said barrel a predetermined distance, said security pin is inserted into said security well, said security pin being of a length sufficient to extend into said housing from said well and prevent further rotation of said barrel. 7

2. A lock comprising a housing, a key barrel mounted in said housing for rotation therein, a pin tumbler mechanism locking said barrel against rotation therein, comprising at least one coacting tumbler and driver received in a well defined by and extending through said housing into said barrel, and means biasing said tumbler and driver in a locking position, at least two security wells defined in said barrel and extending at small angles from said driver-tumbler assembly such that one of said security wells approaches a vertical position upon a small degree of rotation of said barrel in either direction, and security pins carried in wells defined in said housing, said security pins extending transversely of the longitudinal axis of said barrel, each of said security pins being arranged with respect to one of said security wells such that upon unauthorized rotation of said barrel a predetermined distance, a security pin is inserted into one of said security wells, said security pins being of a length sufficient to extend into said housing from a security well and prevent further rotation of said barrel.

3. The lock of claim 2 wherein said key barrel has a key slot defined therein arranged to receive a proper key to lift said tumbler-driver assemblies so that the point of contact between said tumblers and drivers coincides with the peripheral edge of said barrel and allows rotation thereof, and at least one security pin carried in said housing on each side of said tumbler-driver assemblies for cooperation with security wells defined in said barrel.

4. The lock of claim 3 wherein at least one of said security pins is carried in said housing on each side of one of said driver-tumbler assemblies and the tumbler of said one of said assemblies prevents said security pins from being inserted in a security pin receiving well when said barrel is rotated by a proper key.

5. The lock of claim 4 wherein said tumbler of said one of said assemblies is of insufiicient length to prevent one of said security pins from being inserted into a security well upon unauthorized rotation of said barrel.

6. A lock comprising a housing member, a barrel member rotatable therein, a plurality of aligned wells defined in said housing member, a plurality of wells defined in said barrel Inmeber providing a continuation of said housing wells, a driver-tumbler assembly in each well biased toward said barrel to lock said barrel against rotation in said housing, a security pin well defined in said housing on either side of said aligned wells, a security pin in said security pin wells, security pin receiving Wells defined in said barrel, each of said receiving wells having an opening in said barrel generally coinciding with one of said barrel wells and extending at a small angle from said barrel well so that upon predetermined rotation of said barrel in either direction a receiving well is aligned with one of said security pin Wells and arranged to receive a security pin therein, the tumbler adjacent each of said security pins being of a length insufiicient to prevent insertion of a security pin in a receiving Well upon unauthorized rotation of said barrel, but effective to prevent such insertion of a security pin when a proper key is utilized to raise said tumbler and rotate said barrel, said security pins being of greater length than said receiving wells.

7. The lock of claim 6 wherein said security pins are undercut intermediate the ends thereof.

8. The lock of claim 6 wherein said security pin wells are parallel to and on opposite sides of one of said tumbler-driver Wells defined in said housing.

References Cited by the Examiner UNITED STATES PATENTS 1,707,922 4/29 Pepper -421 1,932,363 10/33 Hurd 70419 X 2,222,027 11/40 Golden etal 70-419X 2,836,973 6/58 Schillizzi 7042.1

ALBERT H. KAMPE, Primary Examiner. 

1. A LOCK COMPRISING A HOUSING, A KEY BARREL MOUNTED IN SAID HOUSING FOR ROTATION THEREIN, A PIN TUMBLER MECHANISM LOCKING SAID BARREL AGAINST ROTATION THEREIN COMPRISING AT LEAST ONE COACTING TUMBLER AND DRIVER RECEIVED IN A WELL DEFINED BY SAID HOUSING AND SAID BARREL AND MEANS BIASING SAID TUMBLER AND DRIVER IN A LOCKING POSITION, A SECURITY WELL DEFINED IN SAID BARREL AND EXTENING AT A SMALL ANGLE FROM SAID DRIVER-TUMBLER ASSEMBLY SUCH THAT SAID WELL APPROACHES A VERTICAL POSITION UPON A SMALL DEGREE OF ROTATION OF SAID BARREL, AND A SECURITY PIN CARRIED IN A WELL DEFINED IN SAID HOUSING, SAID SECURITY PIN EXTENDING TRANSVERSELY OF THE LONGITUDINAL AXIS OF SAID BARREL AND BEING ARRANGED WITH RESPECT TO SAID SECURITY WELL SUCH THAT UPON UNAUTHORIZED ROTATION OF SAID BARREL A PREDETERMINED DISTANCE, SAID SECURITY PIN IS INSERTED INTO SAID SECURITY WELL, SAID SECURITY PIN BEING OF A LENGTH SUFFICIENT TO EXTEND INTO SAID HOUSING FROM SIAD WELL AND PREVENT FURTHER ROTATION OF SAID BARREL. 